Zhu Zhi, Wang Jingyi, Li Chaonan, Li Long, Mao Xinguo, Hu Ge, Wang Jinping, Chang Jianzhong, Jing Ruilian
Shanxi Institute of Organic Dryland Farming, Organic Dry Farming of Shanxi Province Key Laboratory, Shanxi Agricultural University, Jinzhong, China.
National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China.
Front Plant Sci. 2022 Aug 23;13:897623. doi: 10.3389/fpls.2022.897623. eCollection 2022.
Leaf rolling is an important agronomic trait in wheat ( L.). Moderate leaf rolling keeps leaves upright and maintains the relatively normal photosynthesis of plants under drought stress. However, the molecular mechanism of wheat leaf rolling remains unclear. Here, we identified a candidate gene that regulates leaf rolling by using a genome-wide association study (GWAS) in a panel of 323 wheat accessions. Phenotype analysis indicated that the leaves of mutants were flatter than that of the wild type under drought condition. A nucleotide variation in the coding region resulted in a substitution of Thr to Lys, which corresponds to two alleles -3A-1 and -3A-2. The leaf rolling index (LRI) of the -3A-1 genotype was significantly lower than that of the -3A-2 genotype. In addition, alleles were associated with canopy temperature (CT) in multiple environments. The CT of the -3A-1 genotype was lower than that of the -3A-2 genotype. Gene expression analysis showed that was mainly expressed in leaves and down-regulated by PEG and ABA treatment. TaMYB5 induces gene expression through the direct binding to the AC -acting element of the promoter of the target gene, which was validated by EMSA (electrophoretic mobility shift assay). Our results revealed a crucial molecular mechanism in wheat leaf rolling and provided the theoretical basis and a gene resource for crop breeding.
叶片卷曲是小麦（Triticum aestivum L.）的一个重要农艺性状。适度的叶片卷曲可使叶片保持直立，并在干旱胁迫下维持植物相对正常的光合作用。然而，小麦叶片卷曲的分子机制仍不清楚。在此，我们通过对323份小麦种质进行全基因组关联研究（GWAS），鉴定出一个调控叶片卷曲的候选基因。表型分析表明，在干旱条件下，突变体的叶片比野生型更扁平。该基因编码区的一个核苷酸变异导致苏氨酸被赖氨酸取代，对应两个等位基因-3A-1和-3A-2。-3A-1基因型的叶片卷曲指数（LRI）显著低于-3A-2基因型。此外，在多个环境中，该等位基因与冠层温度（CT）相关。-3A-1基因型的CT低于-3A-2基因型。基因表达分析表明，该基因主要在叶片中表达，并受聚乙二醇（PEG）和脱落酸（ABA）处理下调。TaMYB5通过直接结合靶基因启动子的AC作用元件诱导该基因表达，这一结果通过电泳迁移率变动分析（EMSA）得到验证。我们的结果揭示了小麦叶片卷曲的关键分子机制，为作物育种提供了理论依据和基因资源。
